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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114557] New: ehcleanup
 cleanup_empty_eh_merge_phis eats a lot of memory
Date: Tue, 02 Apr 2024 08:59:25 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114557

            Bug ID: 114557
           Summary: ehcleanup cleanup_empty_eh_merge_phis eats a lot of
                    memory
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

For the testcase in PR114480 we end up redirecting a lot of edges into
very high in-degree blocks.

(gdb) p new_bb->preds.m_vecpfx
$3 =3D {m_alloc =3D 4095, m_using_auto_storage =3D 0, m_num =3D 3911}

the way the edge redirection works it will resize the target PHI nodes
a lot of time, leaving the old PHIs as garbage until the next GC collection.

For the testcase this piles up to 16GB of garbage.=